Signal device



Feb. 15, 1944.

J. R. M KAY SIGNAL DEVICE Fiied Dec. 3, 1941 I EN TOR I I7770RNEYPatented Feb. 15, 1944 SIGNAL DEVICE John R. MacKay,

West Caldwell, N. J., assignor to Wallace & Tiernan Products,

Inc., Belleville,

N. J., a corporation of New Jersey Application December 3, 1941, SerialNo. 421,451

6 Claims.

This invention relates to lamp changing apparatus for automaticallyreplacing electric lamps which have failed. The invention relates moreparticularly to, and aims to provide, an improved motor means operativeon failure of a positioned lamp for operating lamp mounting andpositioning means to move the failed lamp out of position and a new lampinto position.

Motor means according to the invention comin one direction only, andsaid circuit being electrically associated with the lamp circuit bymeans for applying to said shading coils when normal current flows inthe lamp circuit an E. M. F. of opposite phase from and of greater valuethan the E. M. F. normally induced in the shading coils by the fieldwinding of the motor, whereby a counter-to-normal flow of current is setup through the shading coils, causing or tending to cause reverserotation of the motor, and indexing means which prevents back movement.

Most desirably, the closed circuit of the shading coils includes animpedance of suitable value which is also connected in the lamp circuitin series with the positioned lamp. This impedance may be anon-inductive resistance, but it is now preferred to use a reactance,and I have made for this purpose of applying from the lamp circuit therequired E. M. F. on the shading coils a special reactance devicecomprising a reactance coil and means providing a magnetic circuitassociated with the reactance coil, including a movable core within thecoil which, when normal current flows in the lamp circuit, is moved bymagnetic action as in a solenoid to close an air gap in the magneticcircuit and thereby decrease the reluctance of the magnetic flux pathand increase the reactance of the coil, and which, when current flow inthe lamp circuit stops and the comparatively low voltage current inducedin the shading coils by the field winding of the motor flows through thereactance coil, moves back to a position to open the air gap in themagnetic circuit, thereby increasing the reluctance of the flux path anddecreasing the reactance of the reactance coil, the movable core thenremaining in this position until current again flows in the lampcircuit. This variable reactance device thus provides the impedancerequired for applying to the shading coils, when normal current flows inthe lamp circuit, the desired E. M. F. of greater value than thatinduced in the shading (Cl. Mil-37.1)

coils by the motor field winding, and, when there is no current flowingin the lamp circuit, provides a substantially lower impedance againstthe induced current then flowing in the shading coil circuit.

A full understanding of the invention can best be given by a detaileddescription of a lamp changing apparatus embodying the invention in theform now considered best, and such a description will now be given inconnection with the accompanying drawing, in which:

Fig. 1 is a simplified diagrammatic view of a lamp changing apparatusaccording to the invention;

Fig. 2 is an enlarged detailed view partly in section showing parts ofthe apparatus of Fig. 1;

Fig. 3 is a detailed view taken on line 33 of Fig. 2 but on a smallerscale;

Fig. 4 is a view on the same smaller scale of the rotatable support forthe lamp carrying belt looking from the left of Fig. 2 and showing thecarrier with the disc I! removed and without the carrier belt thereon;and

Fig. 5 is an enlarged detail view taken on line 5-5 of Fig. 2.

The motor means of the present invention may be used for operating anysuitable lamp mounting means comprising a mounting device, or carrier,for a plurality of lamps which is movable for positioning the lampssuccessively, and means for connecting the positioned lamp in a lampcircuit, such, for example, as the mounting means of my applicationSerial No. 299,693, of which this application is a continuation-in-partor a mounting means such as shown in my Patent No. 2,258,575, which forsimplicity is shown in this application.

Referring to the drawing, and first to the lamp mounting means, thelamps are mounted on a carrier belt formed of a plurality of fiat metalplates I0 pivotally connected at their edges. The end of the belt isplaced about a rotary support l l and may carry a weight W which exertsa downward force to help hold the belt in proper position on the rotarysupport. The rotary support, which, as shown in Fig. 2, is mounted on avertical support I5, is formed of two spaced discs [6 and I! of Bakeliteor other insulating material, a metal disc l8 attached to disc 3, andfour metal rods l9 extending between the discs I l and I8 and equallyspaced about the axis of rotation. The discs l6 and I 1 are rotatablymounted on a metal axle 20 extending from and insulated from the supportl5, and the metal disc 18 has a central opening of such size that itdoes not contact with the axle.

The carrier belt is supported on the rods 19 and these rods are spacedaccording to the length of the carrier plates so that the carrier beltwill turn about the support with its plates successively bridging thespace between adjacent supporting rods. Each of the carrier platescarries one of the electric lamps 25, and, asthe carrier belt isadvanced by rotation of the support H, the lamps will be successivelymoved to operative position, which in the apparatus shown is theuppermost position in Figs. 1 and 2, a quarter rotation of the supportserving to move one lamp out of position and the next lamp on thecarrier belt into position. Each carrier belt plate is provided with alamp socket such that the side of the lamp base will be electricallyconnected with the carrier plate. The lamps shown are of the kind havinga prefocused base and are mounted on the carrier plates so that the baseextends through the plate. Whatever type of lamp is used, the sockets onthe plates will be such that the contact terminal at the end of the baseof the positioned lamp will engage a flexible contact strip or brush 3%on the axle 20. Connection is thus made to one contact terminal of thepositioned lamp through the axle 2i], and connection of the otherterminal of the positioned lamp is made from the disc 18 through thesupporting rods l9 and the carrier plate.

The disc N5 of insulating material has four indexing contacts 3|, mostdesirably of rare metal, set below the surface of the disc in radialgrooves 32 in its outer face, the contact pieces extending through thedisc l6 and being conductively connected to the meal disc l8, as shownin Figs. 2 and 3. The contacts 3i and grooves 32 are equally spacedcircumferentially of the disc. A contact 33 carried by a spring 3 3bears against the disc l6 and is shaped and positioned so that when alamp has been moved into operative position the contact 33 will enterone of the grooves 32 and engage the contact 3| therein to close thelamp circuit. As the disc begins to turn when the carrier is moved toposition the new lamp, the contact 33 by its engagement with the side ofthe groove is immediately pushed away from the contact 3| and out of thegroove and then rides on the face of the insulating disc until anotherlamp has been moved into position, whereupon it makes engagement withthe next contact 3| to complete again the lamp circuit.

In Fig. 1, for convenience in diagrammatic illustration, the disc I6 isshown as having peripheral notches in which the contacts 3! are located,and the contacts are shown as connected to a ring from which connectionto the positioned lamp is indicated by line a.

It will be understood that the carrier support I l is intended to bemounted in association with a Fresnel lens or other optical system sothat the positioned lamp will be properly located within the lens orother optical system.

The motor means for turning the carrier support for removing a burnedout or defective lamp and bringing a new lamp into operative positioncomprises a rotary armature alternating current motor 40 of the shadedpole type. Any suitable driving mechanism may be provided between themotor shaft and the carrier support ll. As shown, the motor is mountedon the support l5 and drives the carrier support I I through a reductiongear unit 4! and pinion 42 which meshes with gear teeth formed on theperiphery of the disc It. In order to prevent reverse movement of themotor and carrier support, a ratchet wheel 43 is provided on theconnecting shaft engaged by a pawl Ml. In addition to serving as adetent to prevent backward movement, pawl 44 also serves, in conjunctionwith the tendency of the motor to rotate the carrier backward when alive lamp is in position, as hereinafter explained, as an indexing meansfor determining the exact position of the positioned lamp and formaintaining the lamp accurately in position.

The motor 40 has the usual field winding 45 and two shading coils 46 and4'! which when short circuited cause rotation of the motor in thedirection to move the lamp carrier support clockwise as viewed inFig. 1. These shading coils are connected in a closed circuit whichincludes an impedance 5B which is also connected in the lamp circuit inseries with the positioned lamp. Rather than a non-inductive resistance,the impedance is most desirably a reactance, as indicated in Fig. l, andthe impedance is of such value that whennormal current is flowingthrough the lamp circuit there is applied to the shading coils an E. M.F. of greater value than the E. M. F. normally induced in the shadingcoils by the field winding of the motor, and the connections are suchthat this applied E. M. F. is of opposite phase from the E. M. F.induced in the coils by the field winding. This applied E. M. F. willtherefore cause the motor to rotate in a reverse direction or backward,or to tend to rotat backward against the restraint of the detent means.When, however, no current is flowing in the lamp circuit, the presenceof the impedance 5B in the shading coil circuit does not prevent normalforward rotation of the motor. By thus applying to the shading coilswhen normal current flows in the lamp circuit an E. M. F. of oppositephase from and of greater value than the E. M. F. normally induced inthe shading coils by'thefield winding, the necessity of providing amotor of this kind with additional and oppositely placed shading coilsto effect reverse rotation, as shown in said Patent No.

' 2,258,575, is avoided.

Figs. 2 and 5 show the special variable reactance device referred to inthe introductory part of this specification and which for reasons therepointed out is most desirably used. This variable reactance devicecomprises a reactance coil 51 having comparatively few turns of heavyinsulated wire carried on a tube 52, which may be made of insulatingmaterial or may be a metal cylinder with a longitudinal slot to reduceeddy current losses, and within the tube is a two-part core formed by anupper fixed part 53 and a lower part 54 which is movable within the tubein the manner of a solenoid core, both parts being made of soft orlaminated iron. The movable lower core member 54 has a shading coil 55set into its upper end for holding purposes when the device is energizedby alternating current. The device is. carried by a bracket. 56 formedof two angle plates of soft or laminated iron connected together andmounted on a panel of insulating material 5'! by screws 58. The arm ofone of these angle plates extends over and is secured to the fixed coremember 53, and the arm of the other angle plate holds the lower end ofthe tube The bracket thus forms a U-shaped magnetic return for themagnetic flux created by the coil 53. A spring 59 tends to draw the coremember '56 down away from the member 53 and against a stop plate 60, asshown in Fig. 2, thus opening an air gap 6| between the two coremembers. The tension of the spring 59 is sufiicient to draw the coremember 54 down to the position shown in Fig. 2 when only the normalshading coil current induced by the motor field flows through thereactance coil 5|, but not sufficient to resist the upward pull on thecore member 54 when normal lamp circuit current flows through coil 5|,the core member 54 then being drawn upward by magnetic action to closethe air gap 6 i.

As will be understood, the air gap 5|, formed when the core member 54 isin its retracted position, increases the reluctance of the magneticcircuit formed by the U-shaped bracket 56 and the two core members 53and 54, and the reactance of the coil 5| member 54 is in its upperposition abutting the core member 53. When the core member 54 is in itsupper position abutting the core member 53, the magnetic circuit isimproved and the reluctance of the flux path decreases, thus increasingthe reactance of the coil.

The feed line from the source of alternating current is connected tobinding posts 70 and H carried by a terminal panel 1'2 mounted on thesupport l5. shown in Fig. 1. Current from one side of the sourceconnected to the binding post 19 flows in a circuit including wire 15,reactor coil 5|, wire 75, and through spring contact arm 34, one of thecontacts 3|, and disc It to the positioned lamp, and from the lampcircuit is completed through axle 2|! and wire '18 and binding post H tothe other side of the current source. The field winding of the motor 4|]is, as shown, energized from the same current source, the circuitextending from wire 75 by wire 89 to the motor binding post panel 8| andby wire 32 to one side of the field winding, the other side of the fieldwinding being connected to the terminal post H by wire 83. The shadingcoils 46 and 41 of the motor are connected to binding posts on the panel8| and connected in parallel across the reactance coil 5| by wires 86and 80.

When a live lamp is moved into operative position, it is connected inthe lamp circuit, and the lamp circuit current then flows through thereactance coil 5| and, the core member 54 being by such flow raised toclose the air gap 6 i, produces a voltage drop across the coil, causingcurrent to flow in the shading coil circuit under an E. M. F. which isgreater than the E. M. F. normally in duced in the shading coils by themotor field winding 45 and is opposite in phase. A rotating magneticfield is thus produced by the shading coils in such direction asimmediately to stop the motor and cause it to start rotating backward,that is, in the reverse direction of rotation. This backward rotation isstopped by the indexing pawl 44 and the tendency of the motor to rotatebackward then maintains the lamp in proper focal position at all timesagainst any tendency of vibration or other cause to move the carrier andlamp out of position until the newly postioned lamp fails. On failure ofthe lamp, however, flow of lamp circuit current through the reactancecoil 5| ceases, the core member 54 of the reactor is retracted, therebyre-establishing the air gap BI and reducing the impedance of the coil,and current induced by the motor field winding then flows in the shadingcoil circuit, with the result that normal shading action takes place inthe motor and the motor rotates in its normal forward direction, drivingthe lamp carrier forward, that is, in clockwise direction as viewed inFig. l.

The motor continues to rotate, causing this foris then less than whenthe core The Wiring connections are as Ward movement of the lampcarrier, until a new lamp has been moved into focal position.Immediately on the positioning of the new lamp, there is a momentaryheavy rush of current to the cold filament of the lamp, and the flow ofthis heavy current through the reactance coil 5| raises the core member54 to close the air gap and increase the impedance of the coil, and themotor is immediately stopped and caused to rotate or tend to rotate inthe reverse direction, which backward movement, however, is stopped bythe indexing means; and thereafter, until the newly positioned lampfails, the carrier andlamp are by the tendency of the motor to rotatebackward maintained in accurate position, as before pointed out.

In a flashing light apparatus, that is, apparatus supplied withintermittent current resulting from the introduction of a currentinterrupter in line, it is desirable to provide means whereby when, onfailure of the positioned lamp, the carrier is first moved by thedriving motor energized by the intermittent current, the currentinterrupter is temporarily shunted to permit current to be suppliedcontinuously to the driving motor from the supply line until a new lamphas been moved into operative position, thereby avoiding the relativelyslow lamp-changing operation that would result if the motor weredependent on the intermittent current. Means suitable for this purposeis shown and described in said Patent No. 2,258,575.

The association with the lamp circuit of the closed circuit includingthe shading coil or coils of the driving motor will usually and mostdesirably be by a direct connection as shown in the drawing rather thanby an inductive connection. The closed shading coil circuit willobviously be electrically associated with the lamp circuit in eithercase.

What is claimed is:

1 Lamp changing apparatus, comprising a carrier for a plurality of lampsmovable for posilamp in the circuit, and means for moving the carrier onfailure of the positioned lamp to position another lamp, said meanscomprising an alternating current driving motor having a shading coilconnected in posite phase from E. M. F. induced in the shading coil bythe field of the motor, and indexing means preventing backward movementof the carrier.

2. Lamp changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a lamp circuithaving terminals for connecting the positioned lamp in the circuit, andmeans for moving the carrier on failure of the positioned lamp toposition another lamp, said means comprising an alternating currentdriving motor having a shading coil connected in a closed circuit whichis electrically associated with the lamp circuit by means whereby whennormal current flows in the lamp circuit an E. M. F. of opposite phasefrom and of greater value than the E. M. F. normally induced in theshading coil by the field of the motor is applied to the shading coilwhile normal voltage is applied to the lamp, and indexing means forpreventing backward movement of the carrier.

3. Lamp changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a lamp circuithaving terminals for connecting the positioned lamp in the circuit, andmeans for moving the carrier on failure of the positioned lamp toposition another lamp, said means comprising an alternating currentdriving motor having a shading coil connected in a closed circuit whichincludes an impedance connected in the lamp circuit in series with thepositioned lamp, the impedance being of such value that when normalcurrent flows in the lamp circuit an E. M. F. of opposite phase from andof greater value than the E. M. F. normally induced in the shading coilby the field of the motor is applied to the shading coil but not ofsuiificient value to prevent normal voltage being applied to the lamp,and indexing means for preventing backward movement of the carrier.

4. Lamp changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a lamp circuithaving terminals for connecting the positioned lamp in the circuit, andmeans for moving the carrier on failure of the positioned lamp toposition another lamp, said means comprising an alternating currentdriving motor having a shading coil connected in a closed circuit whichincludes a reactance coil connected in the lamp circuit in series withth positioned lamp, whereby when normal current flows in the lampcircuit an E. M. F. of opposite phase from and of greater value than theE. M. F. normally induced in the shading coil by the field of the motoris applied to the shading coil, and indexing means for preventingbackward movement of the carrier.

5. Lamp changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a, lamp circuithaving terminals for connecting the positioned lamp in the circuit, andmeans for moving the carrier-on failure of the positioned lamp toposition another lamp, said means comprising an alternating currentdriving motor having a shading coil connected in a closed circuit, areactance coil connected in the shading coil circuit in series with theshading coil and also connected in the lamp circuit in series with thepositioned lamp, means for increasing the reactance of the reactancecoil when current flows in the lamp circuit, and indexing means forpreventing backward movement of the carrier.

6. Lamp changing apparatus, comprising a carrier for a plurality oflamps movable for positioning the lamps successively, a lamp circuithaving terminals for connecting the positioned lamp in the circuit, andmeans for moving the carrier on failure of the positioned lamp toposition another lamp, and means comprising an alternating currentdriving motor having a shading coil connected in a closed circuit, areactance coil connected in the shading coil circuit in series with theshading coil and also connected in the lamp circuit in series with thepositioned lamp, means providing a magnetic circuit associated with thereactance coil including a core member movable within the coil andnormally held yieldingly in position to leave an air gap in the magneticcircuit and movable by magnetic action to close said air gap when thelamp circuit current flows through the reactance coil, whereby thereactance of the reactance coil is increased when current flows in thelamp circuit, and indeXing means for preventing backward movement of thecarrier.

JOHN B. MAcKAY.

